lokkutJoin Date: 2009-03-18
Post Count: 1794 |
So, I've been thinking about it, and it would be cool if we could optimise the calculation of gravity enough that it would be able to run properly on a server.
F = (g*m1*m2)/d²
g = Gravity Constant
m1 = mass of particle 1
m2 = mass of particle 2
d = Distance between
if we have 5k parts, that's ( i have no idea how many times we'd have to run the same functions actually, in my head it would make sense for it to be the 4999th triangle number [ = 12mil ] but my head is stupid )
4 multiplications and a divide, a squareroot and 6 more multiplications and 3 subtractions ( for magnitude ).
how possible would it be that this could work?
or would it just run at -1 fps |
|
|
lokkutJoin Date: 2009-03-18
Post Count: 1794 |
qq
thanks :x |
|
eLunateJoin Date: 2014-07-29
Post Count: 13268 |
Use memoizing. |
|
lokkutJoin Date: 2009-03-18
Post Count: 1794 |
is that spelt correctly, if so what is it? |
|
eLunateJoin Date: 2014-07-29
Post Count: 13268 |
Cheeky stuff that stops your function from running again if you've already calculated details for an argument. |
|
lokkutJoin Date: 2009-03-18
Post Count: 1794 |
yes but would the distance not always be different, meaning that it could possibly be a waste of time? |
|
digpoeJoin Date: 2008-11-02
Post Count: 9092 |
local function memorise(func)
local cache = { }
return setmetatable({ }, {
__index = function(_, i)
if not cache[i] then
cache[i] = func(i)
end
return cache[i]
end
})
end
local gravity = memorise(function(mass)
return mass^2
end) |
|
eLunateJoin Date: 2014-07-29
Post Count: 13268 |
It could be worth it... |
|
lokkutJoin Date: 2009-03-18
Post Count: 1794 |
i have no idea how to use metatables erk.
it's also quite late.. so i think i'll sleep on it and get up early to carry on.
i'll probably bump this tommorow, so night
i think i'll be realistic about it tho and keep it down to 2.5k parts
considering i'll have to do :getmass() a whole lot and .magnitude and painful calculations that'll destroy my CPU
i might just ask my freind to run in reality tho, 4th gen intel cpu's are apparently fairly powerful :x |
|
lokkutJoin Date: 2009-03-18
Post Count: 1794 |
just bumping
http://www.roblox.com/games/236308560/Laggy-place
got this far but it still can't handle that many parts
any idea how to optimise more? |
|
|
d² = sqrt(v.x² + v.y² + v.z²)² = v.x² + v.y² + v.z²
Since magnitude is sqrt(v.x² + v.y² + v.z²) and you square it afterwards anyway.
so replace d² with
v.x^2 + v.y^2 + v.z^2
or
v.x*v.x + v.y*v.y + v.z*v.z
that should be faster
|
|
|
Also, how about only memorizing:
g*m1*m2
that's pretty constant. |
|
lokkutJoin Date: 2009-03-18
Post Count: 1794 |
Yeh, did that when reading however people did it.
could it possibly just be due to the fact that roblox has its own physics and tries to make calculations for that? if so i'll probably go remove lal the corescripts or something entirely stupid that won't help anyone |
|
|
also. I don't know if :GetMass() calculates mass over and over, but if it does it may be worth it to safe the mass of every part. |
|
lokkutJoin Date: 2009-03-18
Post Count: 1794 |
Yeh, I memoized it if it's checking the same part, so that it doesn't need to do it twice.
not sure which will be faster though, recalculating mass or saving it in a table. |
|
morashJoin Date: 2010-05-22
Post Count: 5834 |
Doing a calculation 422857792660554352220106420023358440539078667462664674884978240218135805270810820069089904787170638753708474665730068544587848606668381273633721089377278763127939036305846216064390447898698223987192970889621161265296832177550039924219683703146907264472878789790404754884162215226671928410969236910449565971736352948400223840381120644820230857671104502306174894755428309761781724040805324809927809328784055486199364548291211876258248802189173977900050213212598043639244626460770511358846595108675470585833924655225589035474435988347383178988034633008458631510209091509935653820010933047965742556741930917055172805200236075085991197635228755907902043369743123506916831211924495971556267407521462198986233088625998302859864857578749445963115286970886710046268423648178989905454690861391613218344174148807186234448114831209490361196546872767755617886828720269104814092456410341835975604276458161513178575901661071782544156980883359372729995603371371200471049437656291142488605335299499642300699972204918120100819059439140675053265004775533850899097945101551091486907004407119572336026243368132330218709287699196806656569752790422258267841561083376425781032629202687211070274681394351128601502326190649959171897364176378436491219709109840944514895358959103804176941956657834822071749105512752639148381172052604826965162642710094919393332661030104360530459117014557209584714353721948246686793467375904872268133410207860903657108806376616249749507413107077401682180585945526445171409277469230062697511346044174567946735828782261629584248675157379172942724178783105429858245117575511884506574424827574660800238588378492396247368761507015767725898321128632295537044902516387925127590841791744640466913531047347984464996154595542013996317357476301740036796192919942190762895445656261767041799538161133387312823511534152581309087915883638351664797225912944270653557142511737323807232632958121797916679692329687096923901003255574789055099807487061047230646195984955239657612208673866514171699307557691897902675157342075864796345338446835085965490727326321910504064289713096224505162064669468098869917122127404504020684923266241760132910227866687270305284709452526825496617772499645206699836925910690894082637401043498371591126455822280606361394115344316771769934353664284928294436414769615881993661388255577487709937004594753907845149034434521174560594039916268444697661821387470705325559577933196460996662145377564935474169708562389214773222865507182490430016186142192760452307670621142961767274704123616107220009743758647492753665149532164780849075146330071016691313420662882562618283865836983632108760710427516073348347788414796732427080410860761841281888307115098982135338406610652147087046874760995427473673509451553599769040367353385551052571682650317682405743993414862392331981432579182193321898940450865013610998098383993110996355981328001049731588596312131853801205046787642910669365600437305633431984879048998524701293300789344532868156679762880495532846386020133480265279836946393384995675049993707814746561543438930431384237878981847802886009971088695632988347711863122382785963653115132377931373647397429369411499028751972227999545182615488298951151926682112451355318472209990435355949887299922035062039816011086376236539782172380237846650673624510635034423187315338308212043804710999419227821039747552717416043890169723961305549371844836119803565896062025009093664399360172007383613354405094329072476518909502507724675841989412224659392163116352038147362479528539732089309533421910635702805576629720156556510767780805933453631121829561792887673002802450932122778852968418208261778476955644980385691275787372678040959158711733971103165232678060798127609246173504120182666874262805385275843979167609007743380748420751185119102921960339376280986753665085212869255321536787932521882574101866137054328973735862725370178558806639851350386944039604928258820180419178073649693885802597758398892014389747165465973510852605706234402069637065660129535734043582961473427275805630839510667375349259659518575646939723218275780003250593895303820539697558870511543073920827422440516299708739599768461206246629098112368012579891284802505094028916959765079395437191311379314427405135599630375642214527294341797246187597964074239147838993541565834716156858499036773056611353833367087548900413091981676330749041510337597307246885839246941715548295730750618505881581959528992660225626903439573313450666972952115230668696227920947779974336574472673471408928071411283888082693377378077293104110767513639476200610858040596019639058015761002337463869352228385801434957178125581445862930042479404065736859862007914604590255413929950088044710384758990326548097338166940500085452723713571394902463820308668541802838317527668064278489561005755859991718966786449154063570014497194249878920859731254275567514575206399118150736397483102490793841725653421894276769116598153430084637087769510295415136551734675054015239706042571746001089968440498845985477977905031632568489156557231006499726498721480800181770357701502983008879487243887718884416833034708723239505377642232944095773219137582371673924704216723002256883135779230394688900662466182532658490724406767024939579697217467485562998183149665611743997680482094166257463879660305171274925119226367615337524381656217330771650129520988754856467131862602387619964334867961514408328902061082833180891221325853682856469916007952105166960451695430614212305743006877217407155473217957577017595967640563812729153867513698712395570542350999228605975469962186195531354132139126436676900465429996811680550737866770665988027062972502001882845886145344368771455361304414465613369092862748276981946836480550952968681758714859972973082332924094777085275279923304892719633314751563311192746150389219290616780607901383451137066300684376267199885515143681266137319912103235469786756421210624899005553564022924345831264231038363416781719908354140411717740185950606674198348143345444247191436828225654380047860390575922417071802670646875454211626958746795398540784464654140381751149965273621123540880166990280149033225139460832668170930713868826549977374286127789417784752681328371818759103642140881783220739808059714203285309721443041845459183002833408705783138284973283761286182927136745161897366207237396132790944984014154408304074405393067540767126182547597130843470311389815695365971788564022750674237400323621850094765267521941901241387478279883426470873616812485384444012772521050072279315853096279121131160167772077952572613800240684421885453537121341902236379684012385255288607189967725694227433323948595075570839061877450159652184414998155476107548008054192318436948191732631430603548399790783307267636729090980772827355854348032260067472537097785464567761181807367424367391769863758072145859791485033700592994963793369100283444558089838054017635403737133019311293080958287612107380374800660269767842888358265737486556785868822015143046249655995760379768685318192365806469199584071845493606922169776137542662239658644989770921478134709127917460871630220821981434654245065731262683089579031012893360788644107230184805400373136014216229159146992019884148290014414312800903102107833305090238435726779416177246873411503598700003151092815700331081727415624680432977205070450456683898626301702989301145364477416856732512330376477881749036052572605520684370616116539755132541369303867783267208227323664249206432363089268768826650939691861683271739757479552993242406186992420363781929485368098035256331092448215269276219116259145886393677034653480367887126133367116968226450914997055448521259751870084720025674658752403932061045903070039438252019383102480929019684602472171298321628237994627125366359971898374425099120673688383738299653892030662843074547559074235345274029211606091346327684749522046010409575607348155101677203187580089224494752922031093841661588823584993931745149914395557357641584185479831702428523965451087525425464777294595230360946416541997797947136806344915998772409176443137371178542210740572121166868692153240490080384205921192622875440898261478908123698956367080804687628524499897440855677969456909042340530355943524640751677873953113928698614347227572144946891896093294375476741234907792754338349412323060078767610089949156126934038921148370217193387617823370358925817112869563450001367619897145400986643461922197676975930010555225198913002123021780831934330880446592954552165911855939202579781122952065357362914478404946474565003115498072056580360667380889572746464375428055819322299305089287806874537401327100274428317925355003451536693172112088227603942809788645727306979971285649576934354004030728440581746648376658498039958964243370183454151720285337810904113124462432903353964296651109482836884580127588701293156099225044518125460113274986014470437757313881001319276124676116614833528935557503106018449788994378274613854651708241613167681463911870000812845144341406739985430072772303758111613511094355614896323929750846383152930263582535361784837558519666949972251935515953807207838615142130284450051795239760968433198292598921623223582396390262548856855875458198371559008447860086745945709118128793228222051767509371866110013193625845223493949829511199280837860523506412769337548130609594264463425077601147334209139128541628183172262143783062962408149391997187528106367348876678481602342743230027158192404187686545826519361990687336892886715133840245486110982482004482721799496658712257174429044916781194824165631560303473833317665121218052780795958220298330611945164019413315550379662980215357680731124530585915969709973988055743550083279071844959752353594644354789680372126344509423070253995102864458237454677761013556916212309752286152053213998745673034127676503369636682306665552051562491132528926155863868503100849180920507680658265915276163719928694258350604859732273949286080260640627521341007801815105623787926212039424781833439433877206395801115809084190794320195178235740190546595990289617711776195270354051193727229722248442080440098750369411277686593022133010625031862085145076421052980508837197986052557750303949606158442838846866137510968441567309838079394349570013029265177957120625555851951313574029897589283475525334409858911400694449308432874005015554332587793895080241128538758725945136400838324944471346436826148195406004114845870234072926697740631325878634790667698266181501256117692275715291249164821702372884416357600996851100939411444677628186007072278522314941048564396255796808221289935799262208553889221164765220850367706476491496133789353761537391569177822237744837614120253342622508007300513473422771427333106345971803240244226950458090539326689103619381998838844036231795282435495362489670734155948067688515321073064476077859628627852283657244564306449096277517172656954238392941958409527253281659572534531428389629894005886539486824117113929627356938973482935854650278689437014798383826002058208853517073216288725214522205265969614962147884840129004507737252424605074339660818182960296019196314124998538422017695110361380561701016357743542531148669369994130940908368220071936435111978592782493491477052187226546109199597269439152400467901173602521030051886080337084840114810246351288263986170081804888380750203521448348740849154718714478857809574515499505005070789428842888410027877777455981132319940624176532148686316581736774410084063436959989519288310869124517866342559353458242589411390516469440377562665821577845936829909679754548350510473633770839151033854639602753486401635204633884342346714935641429160856846724874244782055113759168236472297793612971080302530934478115527737540458968990354808058309381267323593563098546564376209385371052808344607189076003388781618019853273759498566916704703448438363503416368325266403224174519476678140428319327482851882140344319384445475456765253419659194332132585432270070759038565239668227171300009189122050845185261514627937717597528852978637931711212529529443323757910072909001703558763798612480281463093944391916950129336315045285163539312868586427437296109446101235604877439863299611899755965996608749049271167685268675335991297583209089553296409523640116060078495005377892783750147344122123777907727134146647404489837589487675423294546899354220341669961366698976529978580795899055864050388507083137333076839766882463680992355219727241831735127646189112380485883115569477888101759708977682149644340317924443085170303692214137621194388641989508360339306459037361842937028710758321966607546113761076362543928614316242890754021082233620012309384737312220374269033838579928678572939434168287053763374091938184632261131740934278117918891642447513543478446040549455379834556163353815868441692054518698919434175386663900335756765603264363767906721626620330878425545157208117246381251512669846685887209013144861632560461019513371814585249988176629925142145014710206193190373671380347663431029705222414785030188275106347446241258707937339085095757724316735066885094208761536164440443755860160625837091300574162065273670941888667964570550744724714137001968165215954380698515999483361357521322106131884771926641942395351412233546746461491743013475866037338176532604557402925472279360288926189385899695656876783017186873988763887625972743976062813263446647679413679726184933395074665820441677989806604203937116666336696282569349097348391155869004856032512219241534268522369316036765491047702733521540143168338872968405443296967684036073182435336224865433823598123544167514608340781166661858781733980624199254577853462678039039937557802759942957205281043775666979396838109341118959475766220191217535093638985465283078692370662512323684390235587636228324657161183714078807661162179517887972801841572019639084400269037450381192797170314489871815031319992111563908303017288012610642062005359240278277393918026391717720136125984776933980647063763022608885359937595079088789081791802195768033381968605120487107610874898411568740159953020639098138993261095538868264084012160831040525974539251576403732889086736948366404734622708560040891610782221943405179794550155347682966855320097501905581419914591124181501062255627411231571377358697194374130822027383843815940638571387913337592362330440453487233047240668784133333047898995255221468847973813568083995644533005222551320155267768895412770329278670827490041172076663112783638152343547681663121189086864991380236281775275946061211813342054791801619220346912760381900528012343973598270461499814511324618195658528232044658270082064934680251556511272822083811563192256509945201222666603226059396247019707668580396286975551115189973049085051758765306785758000660424066894170620303846785860257370634352599586885088679654004465187790208942935153217316750113738031466034642429489076322228133763299919641336502028627289268087560036613770607463575515079087982099722660130472907825746908175451952405573791313113170617323191598673971588373108168916968657704150695512947652386134815766967580364762005289060222744531744305498402863048850869557761528650326080941160688570698894762046478500884303973107412774191961697450517110329082815201273888663422631492147090220016940636504812047036016738602290671629816411198202268607961324739550057567564568204754619040423011062371367395995678940884705976859514505017241517746017351430990972615509378334720000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000 (5000! (factorial)) times would be bound to cause major lag. |
|
lokkutJoin Date: 2009-03-18
Post Count: 1794 |
it's not a factorial
it's 1/2*n*(n+1)
|
|
|
If you make a table with all parts as keys and the mass of these as values it would be faster I assume. You could do it like this:
local massParts = {workspace.part = workspace.part:GetMass()}
for part1, mass1 in pairs(massParts) do
for part2, mass2 in pairs(massParts) do
-- do the math
end
end |
|
lokkutJoin Date: 2009-03-18
Post Count: 1794 |
That would be quite a bit faster than I'm currently doing.
|
|
|
And to prevent doubles
local massParts = {workspace.part = workspace.part:GetMass()}
for part1, mass1 in pairs(massParts) do
local last = part1
for part2, mass2 in pairs(massParts) do
if last == nil then
-- do the math
elseif last == part2 then
last = nil
end
end
end
(didn't test) |
|
lokkutJoin Date: 2009-03-18
Post Count: 1794 |
I prefer doing
for i = 1, #blah do
for j = 1, #blah-i do
local k = j+i
local part = parts[k]
end
end
removes the need for the if function
+ i can just work out both forces from one iteration because Part1.force = -Part2.force |
|
morashJoin Date: 2010-05-22
Post Count: 5834 |
Your right, it's not a factorial. lol |
|
lokkutJoin Date: 2009-03-18
Post Count: 1794 |
Yeh, worked that out when calc.exe died heh |
|
|
I think your way is quite a bit slower.
pairs is heavily optimized with non-Lua code
also it think your list will be plain huge (n^2-n) since it needs every possible combination.
|
|